diff --git a/modules/@angular/compiler/src/metadata_resolver.ts b/modules/@angular/compiler/src/metadata_resolver.ts
index bde95f4870..8331cea54e 100644
--- a/modules/@angular/compiler/src/metadata_resolver.ts
+++ b/modules/@angular/compiler/src/metadata_resolver.ts
@@ -351,17 +351,23 @@ export class CompileMetadataResolver {
       }
     });
     moduleMeta.declaredDirectives.forEach((dirMeta) => {
-      dirMeta.entryComponents.forEach((entryComponent) => {
-        if (!moduleMeta.transitiveModule.directivesSet.has(entryComponent.runtime)) {
-          throw new BaseException(
-              `Component ${stringify(dirMeta.type.runtime)} in NgModule ${stringify(moduleMeta.type.runtime)} uses ${stringify(entryComponent.runtime)} via "entryComponents" but it was neither declared nor imported into the module!`);
+      dirMeta.entryComponents.forEach((entryComponentType) => {
+        if (!moduleMeta.transitiveModule.directivesSet.has(entryComponentType.runtime)) {
+          this._addDirectiveToModule(
+              this.getDirectiveMetadata(entryComponentType.runtime), moduleMeta.type.runtime,
+              moduleMeta.transitiveModule, moduleMeta.declaredDirectives);
+          this._console.warn(
+              `Component ${stringify(dirMeta.type.runtime)} in NgModule ${stringify(moduleMeta.type.runtime)} uses ${stringify(entryComponentType.runtime)} via "entryComponents" but it was neither declared nor imported into the module! This warning will become an error after final.`);
         }
       });
     });
     moduleMeta.entryComponents.forEach((entryComponentType) => {
       if (!moduleMeta.transitiveModule.directivesSet.has(entryComponentType.runtime)) {
-        throw new BaseException(
-            `NgModule ${stringify(moduleMeta.type.runtime)} uses ${stringify(entryComponentType.runtime)} via "entryComponents" but it was neither declared nor imported!`);
+        this._addDirectiveToModule(
+            this.getDirectiveMetadata(entryComponentType.runtime), moduleMeta.type.runtime,
+            moduleMeta.transitiveModule, moduleMeta.declaredDirectives);
+        this._console.warn(
+            `NgModule ${stringify(moduleMeta.type.runtime)} uses ${stringify(entryComponentType.runtime)} via "entryComponents" but it was neither declared nor imported! This warning will become an error after final.`);
       }
     });
   }
diff --git a/modules/@angular/core/test/linker/entry_components_integration_spec.ts b/modules/@angular/core/test/linker/entry_components_integration_spec.ts
index 2b425d288e..2766d25951 100644
--- a/modules/@angular/core/test/linker/entry_components_integration_spec.ts
+++ b/modules/@angular/core/test/linker/entry_components_integration_spec.ts
@@ -7,20 +7,33 @@
  */
 
 import {AsyncTestCompleter, beforeEach, ddescribe, xdescribe, describe, expect, iit, inject, beforeEachProviders, it, xit,} from '@angular/core/testing/testing_internal';
-import {TestComponentBuilder, configureModule} from '@angular/core/testing';
+import {TestComponentBuilder, configureModule, configureCompiler} from '@angular/core/testing';
 import {Component, ComponentFactoryResolver, NoComponentFactoryError, forwardRef, ANALYZE_FOR_ENTRY_COMPONENTS, ViewMetadata} from '@angular/core';
 import {stringify} from '../../src/facade/lang';
+import {Console} from '../../src/console';
 
 export function main() {
   describe('jit', () => { declareTests({useJit: true}); });
   describe('no jit', () => { declareTests({useJit: false}); });
 }
 
+class DummyConsole implements Console {
+  public warnings: string[] = [];
+
+  log(message: string) {}
+  warn(message: string) { this.warnings.push(message); }
+}
+
 function declareTests({useJit}: {useJit: boolean}) {
   describe('@Component.entryComponents', function() {
-    beforeEach(() => { configureModule({declarations: [MainComp, ChildComp, NestedChildComp]}); });
+    var console: DummyConsole;
+    beforeEach(() => {
+      console = new DummyConsole();
+      configureCompiler({useJit: useJit, providers: [{provide: Console, useValue: console}]});
+      configureModule({declarations: [MainComp, ChildComp, NestedChildComp]});
+    });
 
-    it('should error if the component was not declared nor imported by the module',
+    it('should warn and auto declare if the component was not declared nor imported by the module',
        inject([TestComponentBuilder], (tcb: TestComponentBuilder) => {
 
          @Component({selector: 'child', template: ''})
@@ -31,9 +44,14 @@ function declareTests({useJit}: {useJit: boolean}) {
          class SomeComp {
          }
 
-         expect(() => tcb.createSync(SomeComp))
-             .toThrowError(
-                 `Component ${stringify(SomeComp)} in NgModule DynamicTestModule uses ${stringify(ChildComp)} via "entryComponents" but it was neither declared nor imported into the module!`);
+         const compFixture = tcb.createSync(SomeComp);
+         const cf = compFixture.componentRef.injector.get(ComponentFactoryResolver)
+                        .resolveComponentFactory(ChildComp);
+         expect(cf.componentType).toBe(ChildComp);
+
+         expect(console.warnings).toEqual([
+           `Component ${stringify(SomeComp)} in NgModule DynamicTestModule uses ${stringify(ChildComp)} via "entryComponents" but it was neither declared nor imported into the module! This warning will become an error after final.`
+         ]);
        }));
 
 
diff --git a/modules/@angular/core/test/linker/ng_module_integration_spec.ts b/modules/@angular/core/test/linker/ng_module_integration_spec.ts
index 986129fcb7..24740b3d17 100644
--- a/modules/@angular/core/test/linker/ng_module_integration_spec.ts
+++ b/modules/@angular/core/test/linker/ng_module_integration_spec.ts
@@ -164,16 +164,6 @@ function declareTests({useJit}: {useJit: boolean}) {
                 `Can't export pipe ${stringify(SomePipe)} from ${stringify(SomeModule)} as it was neither declared nor imported!`);
       });
 
-      it('should error when using an entryComponent that was neither declared nor imported', () => {
-        @NgModule({entryComponents: [SomeComp]})
-        class SomeModule {
-        }
-
-        expect(() => createModule(SomeModule))
-            .toThrowError(
-                `NgModule ${stringify(SomeModule)} uses ${stringify(SomeComp)} via "entryComponents" but it was neither declared nor imported!`);
-      });
-
       it('should error if a directive is declared in more than 1 module', () => {
         @NgModule({declarations: [SomeDirective]})
         class Module1 {
@@ -281,6 +271,21 @@ function declareTests({useJit}: {useJit: boolean}) {
             .toBe(SomeComp);
       });
 
+      it('should warn and auto declare when using an entryComponent that was neither declared nor imported',
+         () => {
+           @NgModule({entryComponents: [SomeComp]})
+           class SomeModule {
+           }
+
+           const ngModule = createModule(SomeModule);
+           expect(ngModule.componentFactoryResolver.resolveComponentFactory(SomeComp).componentType)
+               .toBe(SomeComp);
+
+           expect(console.warnings).toEqual([
+             `NgModule ${stringify(SomeModule)} uses ${stringify(SomeComp)} via "entryComponents" but it was neither declared nor imported! This warning will become an error after final.`
+           ]);
+         });
+
       it('should entryComponents ComponentFactories via ANALYZE_FOR_ENTRY_COMPONENTS', () => {
         @NgModule({
           declarations: [SomeComp],